The present invention generally relates to an ink transferring printing mechanism, and more particularly to an ink transferring printing mechanism capable of rapidly printing an image on a recording sheet.
An ink transferring printing mechanism according to the present invention has an ink sheet including a resistance layer, a conductive layer, and an ink layer which are stacked in this order. In this ink transferring printing mechanism, a recording current supplied to each of a plurality of recording electrodes flows into the resistance layer and the conductive layer so that ink in the ink layer is transferred, by heat which is generated by the recording current in the resistance layer, to a recording sheet. Conventionally, to carry out rapid printing, the following ink transferring printing mechanism, in which the ink in the ink layer is preheated, has been proposed.
FIG. 1 is a cross sectional view showing an example of a conventional printing mechanism. Referring to FIG. 1, an ink sheet 22 is put between a recording electrode 21 and a recording sheet 29. The ink sheet 22 has a resistance layer 26, a conductive layer 27 and an ink layer 28 which are stacked in this order. A preheating electrode 25 is provided at a side of the recording electrode 21 so as to be separated from the recording electrode 21. A feedback electrode 23 is provided at another side of the recording electrode 21 so as to be also separated from the recording electrode 21. The preheating electrode 25 and the feedback electrode 23 are respectively in contact with a surface of the resistance layer 26 in the ink sheet 22. The ink sheet 22 is transported in a direction going from the preheating electrode 25 toward the feedback electrode 23, as indicated by an arrow in FIG. 1.
A recording current corresponding to image information supplied to the recording electrode 21 flows, via the resistance layer 26 and the conductive layer 27 of the ink sheet 22, in the feedback electrode 23. When the current flows via the resistance layer 26 and the conductive layer 27, the heat is generated in the resistance layer 26. Then, ink in the ink layer 28 of the ink sheet 22 is transferred by the heat generated in the resistance layer 26 to the recording sheet 29. Therefore, the image corresponding to the image information is formed on the recording sheet 29.
When an image is being recorded, a preheating current supplied to the preheating electrode 25 also flows via the resistance layer 26 and conductive layer 27 in the feedback electrode 23. Thus, the ink in the ink layer 28 is preheated by the heat generated in the resistance layer 26, through which the preheating current flows, and then the preheated ink is transferred, by the heat generated by the recording current supplied via the recording electrode 21 to the feedback electrode 23, to the recording sheet 29.
In the conventional printing mechanism, the ink in the ink layer 26 of the ink sheet 22 is preheated by the preheating electrode 25 before the ink is transferred by the recording electrode 21 to the recording sheet 29. However, the recording electrode 21 and the preheating electrode 25 are separated from each other so that the temperature of the preheated ink decreases before the ink is heated by the recording current supplied through the recording electrode 21. That is, it is difficult to sufficiently preheat the ink.